Yarn cutter for circular knitting machines

ABSTRACT

A yarn cutter for circular knitting machines, particularly for yarn changers of double cylinder knitting machines, comprising at least one scissor member consisting of a striplike element mounted to slide backwards and forwards adjacent to a fixed blade. Pressed against the striplike element on the side opposite that adjacent the fixed blade, is a body of elastically yieldable material such as plastic material. This body occupies at least part of the width of the striplike element for the retention therebetween of the yarn or yarns after the cutting thereof. Means are also provided for adjusting the pressure of the elastic body on the striplike element.

United States Patent Lonati [451 Apr. 16, 1974 [541 YARN CUTTER FORCIRCULAR KNITTING MACHINES [76] Inventor: Francesco Lonati, via S. P01011,

Brescia, Italy [22] Filed: Mar. 20, 1972 [21] Appl. No.: 235,902

[30] Foreign Application Priority Data Apr, 8, 1971 Italy 22894/71 [52]US. Cl 66/14, 66/134, 66/140 R, 7 66/145 R [51] Int. Cl D04b 15/60 [58]Field of Search 66/l34, 145 R, 14, 140 R- [56] References Cited UNITEDSTATES PATENTS 2,252,214 8/1941 St. Pierre 66/134 3,552,149 l/l97lLonati' 778,164 12/1904 Barratt 56/140 R 6/1941 Lawson et al 66/13412/1942 Hilker et al 66/134 Primary Examiner-Robert R. Mackey Attorney,Agent, or Firm-Guido Modiano, Dr.; Albert Josif, Dr. I

[5 7] ABSTRACT A yarn cutter for circular knitting machines,particularly for yarn changers of double cylinder knitting machines,comprising at least one scissor member consisting of a striplike elementmounted to slide backwards and forwards adjacent to a fixed blade.Pressed against the striplike element on the side opposite that adjacentthe fixed blade, is a body of elastically yieldablc material such asplastic material. This body occupies at least part of the width of thestriplike element for the retention therebetween of the yarn or yarnsafter the cutting thereof. Means are also provided for adjusting thepressure of the elastic body on the striplike element.

1 Claim, 5 Drawing Figures YARN CUTTER FOR CIRCULAR KNITTING MACHINESBACKGROUND OF THE INVENTION The present invention relates to a yarncutter for circular knitting machines, particularly adapted forattachment to yarn changers of double cylinder knitting machines.

When a stocking is being knitted on a circular knitting machine of thedouble cylinder type, it may be required to replace the yarn used in themanufacture with another of a different type, different count ordifferent color, and this is done by changing the yarn carrier by meansof yarn changers, which are fed with different yarns.

When a yarn carrier is disconnected from the manufacturing process, itis brought into the rest position and simultaneously the yarn stretchedbetween the last needle which has taken said yarn and the correspondingyarn carrier is cut by a yarn cutter comprising a mobile driven metalblade which after cutting the yarn in co-operation with a metal counterblade, retainsit;

In yarn cutters of known type certain disadvantages arise, among whichis that of a not always effective retention of the various-yarns,because of the fact that the retention adjustment is made for averagevalues and is not satisfactory for retaining yarns of the smallestSUMMARY OF THE INVENTION,

An object of the present invention is to largely obviatetheaforementioned disadvantages relative to known devices, by providing ayarn" cutter of rational conception, excellent operation and easyadjustment, by means of which the retention of yarns of different typeor count, either single or'combined, is assured. Another importantobject of the invention is to provide a yarn cutter in which thenecessary periodical sharpening operations are simplified.

Another object of the invention is to provide a yarn cutter of easyconstruction and low cost.

These and further objects are attained by the yarn cutter for circularknitting machines, according to the invention, comprising at least onescissor member consisting of a striplike element mounted to slidebackwards and forwards in the direction of its own length adjacent to afixed blade and characterized in that a body of elastically yieldablematerial such as plastic material or the like is disposed pressed tosaid striplike element on the side opposite that adjacent to said fixedblade, and occupying at least part of the width of said striplikeelement, for the retention between this latter and said body of the yarnor yarns immediately after their cutting, means being provided foradjusting the pressure of said body on said striplike, element.

BRIEF DESCRIPTION OF THE DRAWING Further characteristics and advantagesof the invention will be more evident from the detailed description of apreferred but not exclusive embodiment of a yarn cutter, according tothe invention, illustrated by way of example in the accompanying drawingin which:

FIGS. 1 and 2 are perspective views of the yarn cutter according to theinvention, seen from two opposite sides respectively;

FIG. 3 is a perspective view ofa detail of the same device;

FIG. 4 is a vertical section through the device with a scissor member inthe open position;

FIG. 5 is a vertical section through the device with all scissor membersin the closed position.

DESCRIPTION OF THE PREFERRED EMBODIMENT With reference to said figures,the yarn cutter according to the invention (by the term yarn. cutter ismeant a device which in addition to cutting also provides for retainingthe yarns as the changes are made) comprises a support structure 1 whichextends upwards in the .form of a plate la which is fixed in an inclinedposition near the two cylinders 1b (FIG. 1) of the knitting machine andnear a yarn changer (not shown) provided to the left of said yarncutter, with reference to FIG. 1.

Various scissor members (six in the example shown) are associated withthe plate body la, each of them comprising a striplike element 2 mountedto slide backwards and forwards in the direction of its own length andterminating upwards with a hook portion 2a.

The striplike elements 2 are mounted parallel one to the other incorresponding guide grooves and are adjacent to a stationary plateelement defining a single blade 3 fixed to the internal side of theplate body la by means of screws which pass through slots 3a which allowthe height of the blade to be adjusted. The cutting edge 3b of the bladeis-to the top, slightly below the extremities of the hook portions 2a ofthe striplike elements 2 when these are in the rest position. By thisarrangernent, the cutting edge 3b of the blade 3 cuts the yarns afterthey have been hooked by the hook portions 2a and pulled down by them.

At each striplike element 2 a yarn retaining block 4 of elasticallyyieldable material is provided, preferably of the material commonlyknown as nylon or a like material, said block being pressed towards thestriplike element 2 by a corresponding flat metal spring 5 embedded atits lower end into the plate body la, its elastic force being adjustableby means of a screw 6 which, after adjustment, is locked by anotherscrew 7 disposed perpendicularly to screw 6. In the example shown sixblocks 4 are provided disposed one beside the other in a quadrangularspace formed at the top of the plate body 1a.

For moving the striplike elements 2 backwards and forwards, each of themis provided with a recess 8 into which the projecting end 9 of a lever10 pivoted at 11 to the fixed structure 1 engages. Each lever 10 ismoved by a Bowden wire whose cable is fixed to the lever and passesthrough slots 13 in a shaped plate member 14 rigid with the fixed part1, and its corresponding sheath 16 is fixed to said plate member 14. Thelevers 10 are moved against the reaction of corresponding springs 15which tend to keep the extremities 9 of said levers 10 lowered so thatnormally the striplike elements 2 are disposed in the lowered positionwith their hook portions 2a close to the sharpened edge 3b of the blade3.

At the top of the plate member la there is a wire-like member 17 ofarched shape, disposed transversly and projecting for guiding the yarnsduring the stage immediately preceding their cutting. Close to saidwire-like member 17 there is a further wire-like member 18 which stopsthe machine should the yarn not be cut. In fact, the yarn which has notbeen cut is taken by the hook portion of member 18 and resilientlydisplaces this member 18 which acts on a microswitch (not shown) whichstops current supply to the machine.

Theyarn cutter according to the invention operates in the followingmanner.

The device comes into operation when yarns are to be changed, i.e., whenthe yarn carriers (not shown) of the yarn changer move, by knownmechanisms, from a rest position to a working position and vice versa,so as to feed certain yarns to the knitting machine and exclude others.

When a yarn carrier is moved into the rest position, i.e. when thecorresponding yarn is withdrawn from the needle cylinders, said yarnmust be cut and retained in such a manner as to be ready for re-entryinto the machine. This is done by raising the desired striplike element2 by pulling a cable 12 immediately before the movement of the yarncarrier, said element 2 again assuming for example the position shown inFIGS. 1, 2 and 4.

When the yarn is removed from the machine, it passes between thewire-like member 17 and the plate body 1, being thus guided against theportion 2a of the previously raised striplike element 2. Immediatelyafterwards the striplike element 2 is driven downwards by the action ofthe corresponding spring 15, after the cable 12 has been released. Asthe hook portion 2a is lowered, the yarn is cut by the cutting edge 3bof the blade 3, and the same yarn is retained by pressure between theportion 2a and the corresponding nylon block 4. The arrangement shown inFIG. 5 is thus attained, in which the yarn has been cut and is retainedbetween the hook portion 2a and the block 4 until the yarn is reinsertedinto the machine.

A very efficient retention action is set up on the yarn by its locationbetween a metal member (2) and a member of yieldable plastic material(4), as excellent adherence is obtained due to a partial defonnation ofthe block 4.

The disposition according to the invention is particularly advantageouswhen two yarns of different type or different count have to be cut andretained simultaneously. In this case the partial deformability of theblock 4 of plastic material assures the simultaneous retention of two oreven more yarns, independently of their characteristics. Thus, forexample, if two yarns of different count are used, the yarn of smallerdiameter does not escape as frequently happens with traditional devices,because the elasticity of the material which constitutes the blocks 4assures excellent adaptability and adherence even in the case of verydifferent yarn diameters.

A further advantage of the device according to the invention is thepossibility of adjusting the pressure of each block 4 on itscorresponding striplike element 2 independently of the other blocks, byadjusting the screws 6. In this manner different pressures can be set upaccording to the various characteristics of the yarn to be retained atone or another of the scissor members.

The screws 7 lock the screws 6 after their adjustment so as to preventany loosening due to vibrations during use. The wire-like member 18serves for automatically stopping the machine (by closing a contactwhich inserts a relay) should the yarn not be cut because the hookportions 20 do not rise, or for other reasons. The thread cutteraccording to the invention is easily sharpened by a single operation onthe edge 3b of the blade 3, which can be carried out after disassemblingit.

It can be seen that the yarn cutter according to the invention is ofreliable operation, and eliminates the danger of the yams escaping onchanging, with consequent reduction in the quantity of manufacturedarticles which have to be rejected. As stated, the device according tothe invention is particularly advantageous for the production of platedknitwear.

The device according to the invention is appicable to all circularknitting machines, of one or two cylinders and one or more foods.

The invention so conceived is susceptible to numerous modifications allof which fall within the scope of the inventive idea.

I claim:

1. A yarn cutting and retaining device for circular knitting machines,particularly double cylinder knitting machines, comprising incombination a fixed support structure arranged adjacent the needlecylinders, a plurality of elongated strip-like elements arrangedadjacent to each other and each having a hooked end for taking a yarn,said strip-like elements being slidable inside said support structurealong their own length and defining a plurality of movable cuttingblades, a stationary plate element arranged contacting all of saidstriplike elements at one face thereof and having a sharpened edgeextending transverse to said strip-like elements for defining therewitha plurality of independently operating cutting units, a plurality ofyarn retaining blocks of yieldable plastic material each associated toone of said strip-like elements at the face thereof opposite to saidstationary plate element, said retaining blocks having a width providedfor simultaneously retaining more than one yarn, spring means eachhaving one end engaging one of said yarn retaining blocks for pressingit against the corresponding strip-like element, adjusting screwsarranged within said support structure and acting on said spring meansfor adjusting the elastic force thereof against said yarn retainingblocks and means for selectively actuating said strip-like elements forcutting, retaining and releasing said yarns.

1. A yarn cutting and retaining device for circular knitting machines,particularly double cylinder knitting machines, comprising incombination a fixed support structure arranged adjacent the needlecylinders, a plurality of elongated striplike elements arranged adjacentto each other and each having a hooked end for taking a yarn, saidstrip-like elements being slidable inside said support structure alongtheir own length and defining a plurality of movable cutting blades, astationary plate element arranged contacting all of said strip-likeelements at one face thereof and having a sharpened edge extendingtransverse to said strip-like elements for defining therewith aplurality of independently operating cutting units, a plurality of yarnretaining blocks of yieldable plastic material each associated to one ofsaid strip-like elements at the face thereof opposite to said stationaryplate element, said retaining blocks having a width provided forsimultaneously retaining more than one yarn, spring means each havingone end engaging one of said yarn retaining blocks for pressing itagainst the corresponding strip-like element, adjusting screws arrangedwithin said support structure and acting on said spring means foradjusting the elastic force thereof against said yarn retaining blocksand means for selectively actuating said strip-like elements forcutting, retaining and releasing said yarns.